The present invention relates to a vacuum brake booster for a motor vehicle brake system, comprising a force input member movable along a longitudinal axis, which force input member is coupled or couplable to a brake pedal, a control valve arrangement actuable by the force input member, a chamber arrangement arranged within a housing, having at least one working chamber and at least one vacuum chamber, which are separated from one another by a movable wall, and a force output member for transmitting an actuating force, wherein the at least one working chamber can be connected selectively with a vacuum source or the atmosphere, wherein the control valve arrangement has a control valve housing, which is coupled with the at least one movable wall for common movement, and wherein the control valve arrangement has a force transmitting arrangement provided with an axial play, which is arranged in the force transmitting path between the force input member and force output member. The invention further relates to a method for manufacturing a brake booster of this type.
A vacuum brake booster of this type is known from the prior art. For example, the document DE 10 2008 025 712 A1 shows such a brake booster. In this prior art, it was realised that noises may occur when the energy freed on releasing the brakes results in an audible striking of a travel limiting element against the housing. Striking noises of this type are undesirable on the part of the motor vehicle manufacturers. This problem is combated according to the prior art by fitting various damping arrangements on or between contact surfaces of components striking against one another, in order thus to damp the striking.
However, it has been found that undesirable noises may also occur in the region of the force transmitting arrangement between the force input member and the force output member. This force transmitting arrangement is usually designed in a manner provided with an axial play, which is necessary in particular in order to avoid too abrupt a response of the brake booster to a brake actuation. Owing to the intentionally provided axial play within the force transmitting arrangement, however, there is the problem, according to the realization of the inventors, that vibrations occurring due to driving may be transmitted to the components of the force transmitting arrangement of the brake booster and these components thus generate undesirable vibration noises. Vibration noises of this type cannot be eliminated by damping arrangements, because damping arrangements in the region of the force transmitting arrangement may interfere with the response characteristic. Moreover, they would be subjected to high mechanical loads and thus wear.